Guide catheters are used to place diagnostic catheters, treatment catheters, electrode leads and the like in desired locations within the body of a patient. A guide catheter typically includes an elongated sheath that is inserted into a blood vessel or another portion of the body. A second catheter or lead is introduced through a lumen defined by the sheath. To enable precise positioning of a second catheter or lead, the guide catheter sometimes incorporates a radiopaque marker or radiopaque material to promote visibility. Using fluoroscopic imaging techniques, the physician can visualize the radiopaque portion of the guide catheter and place the second catheter or electrode lead in a desired position.
One particular area within the vasculature that may be difficult to locate is an ostium of a vessel. The ostium of a vessel is an opening, aperture, or orifice located at the point of origin of the vessel. Typically, a vessel branches off from a larger parent or main vessel. For example, the aorta gives rise to the coronary arteries; the opening at the origin of each coronary artery as it branches from the aorta is referred to as an ostium. It may be desirable to locate the ostium of a branch vessel in order to access the branch vessel, such as when treating a lesion or antherosclerotic plaque located within the branch vessel. It also may be desirable to locate the ostium of a branch vessel when a lesion is located at the ostium, e.g., an ostial lesion. It may also be desirable to locate a fenestration of a previously-implanted graft that aligns with an ostium of a branch vessel or an ostium of a re-directed internal mammary artery or a grafted saphenous vein. In any case, an operator often utilizes a guide catheter to locate a target ostium within the body.
When locating a target ostium, radiopaque contrast liquid is often injected into the patient and X-ray is utilized to visualize the vasculature and ostium location. Although contrast liquid may be effective in locating the ostium, contrast is cytotoxic and high amounts thereof can lead to contrast-induced nephropathy and complications with the patient such as renal failure. In addition, an ostium may be particularly difficult to locate due to a non-standard location or the individual anatomy of the patient, thus leading to repeated injections of contrast and higher X-ray exposure for the patient as well as higher X-ray exposure for the entire staff in the operating room. Since the contrast agent is cytotoxic, the administered amount is monitored and if a threshold limit is reached prior to successfully locating the target ostium, the procedure must nonetheless be stopped.
Accordingly there is a need in the art for improvements for locating a target ostium. Embodiments hereof relate to an ostium locating system for quickly and accurately locating a target ostium without requiring the use of a contrast agent or at least reducing the quantity of the contrast agent and minimizing X-ray exposure.